A Galactic Plane Defined by the Milky Way H ii Region Distribution

Wenger, Trey V.; Armentrout, W. P.; Balser, Dana S.; Bania, T. M.

doi:10.3847/1538-4357/aaf571

Cited by 32 publications

(31 citation statements)

References 45 publications

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“…In our calculations we assumed that the Sun is located in the Galactic midplane, which is consistent with results from the most recent studies (Anderson et al 2019;Reid et al 2019). However, previous studies and observations found that the Sun has a vertical offset of z offset ∼ 25 pc from the IAU definition of the 11 We note that the presence of these incorrect distance assignments do not change our general conclusion about the warp of the Galactic disc towards positive z gal values.…”

Section: Vertical Distribution Of the 13 Co Emissionsupporting

confidence: 85%

“…In our calculations we assumed that the Sun is located in the Galactic midplane, which is consistent with results from the most recent studies (Anderson et al 2019;Reid et al 2019). However, previous studies and observations found that the Sun has a vertical offset of z offset ∼ 25 pc from the IAU definition of the Galactic midplane (Goodman et al 2014;Bland-Hawthorn & Gerhard 2016).…”

Section: Vertical Distribution Of the 13 Co Emissionsupporting

confidence: 85%

“…The small strips at the top of the individual panels show where the median value is higher (blue) or lower (red) compared to the opposite BDC run, with the strength of the colour corresponding to the magnitude of the difference. The dashed horizontal line indicates the GRS velocity resolution (0.21 km s −1 ).location of the Galactic midplane(Anderson et al 2019;Reid et al 2019).…”

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confidence: 99%

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Autonomous Gaussian decomposition of the Galactic Ring Survey

Riener

Kainulainen

Henshaw

et al. 2020

A&A

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Knowledge about the distribution of CO emission in the Milky Way is essential to understanding the impact of the Galactic environment on the formation and evolution of structures in the interstellar medium. However, our current insight as to the fraction of CO in the spiral arm and interarm regions is still limited by large uncertainties in assumed rotation curve models or distance determination techniques. In this work we use the Bayesian approach from Reid et al. (2016, ApJ, 823, 77; 2019, ApJ, 885, 131), which is based on our most precise knowledge at present about the structure and kinematics of the Milky Way, to obtain the current best assessment of the Galactic distribution of 13CO from the Galactic Ring Survey. We performed two different distance estimates that either included (Run A) or excluded (Run B) a model for Galactic features, such as spiral arms or spurs. We also included a prior for the solution of the kinematic distance ambiguity that was determined from a compilation of literature distances and an assumed size-linewidth relationship. Even though the two distance runs show strong differences due to the prior for Galactic features for Run A and larger uncertainties due to kinematic distances in Run B, the majority of their distance results are consistent with each other within the uncertainties. We find that the fraction of 13CO emission associated with spiral arm features ranges from 76 to 84% between the two distance runs. The vertical distribution of the gas is concentrated around the Galactic midplane, showing full-width at half-maximum values of ~75 pc. We do not find any significant difference between gas emission properties associated with spiral arm and interarm features. In particular, the distribution of velocity dispersion values of gas emission in spurs and spiral arms is very similar. We detect a trend of higher velocity dispersion values with increasing heliocentric distance, which we, however, attribute to beam averaging effects caused by differences in spatial resolution. We argue that the true distribution of the gas emission is likely more similar to a combination of the two distance results discussed, and we highlight the importance of using complementary distance estimations to safeguard against the pitfalls of any single approach. We conclude that the methodology presented in this work is a promising way to determine distances to gas emission features in Galactic plane surveys.

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Section: Vertical Distribution Of the 13 Co Emissionsupporting

confidence: 85%

“…In our calculations we assumed that the Sun is located in the Galactic midplane, which is consistent with results from the most recent studies (Anderson et al 2019;Reid et al 2019). However, previous studies and observations found that the Sun has a vertical offset of z offset ∼ 25 pc from the IAU definition of the Galactic midplane (Goodman et al 2014;Bland-Hawthorn & Gerhard 2016).…”

Section: Vertical Distribution Of the 13 Co Emissionsupporting

confidence: 85%

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confidence: 99%

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Autonomous Gaussian decomposition of the Galactic Ring Survey

Riener

Kainulainen

Henshaw

et al. 2020

A&A

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“…Following Liang et al (2020) we set r max p = 1.5 , which is comparable to but slightly larger than half of the MaNGA spatial resolution (2.5 , corresponding to ∼ 1.5 kpc at the MaNGA median redshift z = 0.03). Due to the limited resolution one cannot resolve individual Hii regions whose sizes typically range from a few to hundreds of parsecs (e.g., Kennicutt 1984;Kim & Koo 2001;Hunt & Hirashita 2009;Lopez et al 2011;Anderson et al 2019). Therefore, the ionized gas regions identified from MaNGA may contain a few to hundreds of individual Hii regions, or be a mixture of DIG and Hii regions.…”

Section: Identifying Ionized Gas Regionsmentioning

confidence: 99%

Estimating Dust Attenuation From Galactic Spectra. II. Stellar and Gas Attenuation in Star-forming and Diffuse Ionized Gas Regions in MaNGA

Niu

et al. 2021

ApJ

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We investigate the dust attenuation in both stellar populations and ionized gas in kiloparsec-scale regions in nearby galaxies using integral field spectroscopy data from MaNGA MPL-9. We identify star-forming (H ii) and diffuse ionized gas (DIG) regions from MaNGA data cubes. From the stacked spectrum of each region, we measure the stellar attenuation, E B − V star , using the technique developed by Li et al., as well as the gas attenuation, E B − V gas , from the Balmer decrement. We then examine the correlation of E B − V star , E B − V gas , E B − V gas − E B − V star , and E B − V star / E B − V gas with 16 regional/global properties, and for regions with different Hα surface brightnesses (ΣHα ). We find a stronger correlation between E B − V star and E B − V gas in regions of higher ΣHα . The luminosity-weighted age (t L ) is found to be the property that is the most strongly correlated with E B − V star , and consequently, with E B − V gas − E B − V star and E B − V star / E B − V gas . At fixed ΣHα , log 10 t L is linearly and negatively correlated with E B − V star / E B − V gas at all ages. Gas-phase metallicity and ionization level are important for the attenuation in the gas. Our results indicate that the ionizing source for DIG regions is likely distributed in the outskirts of galaxies, while for H ii regions, our results can be well explained by the two-component dust model of Charlot & Fall.

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“…Within the Vela region, the Gum Catalogue 8 and RCW Catalogue (Rodgers et al 1960) provide the identification of several H regions observable in the southern hemisphere. Other candidate and known H regions are also collected in the WISE H Catalogue (Anderson et al 2019), in Wenger et al (2021), and in SIMBAD. In the foreground, at ≈300-450 pc away is the Gum Nebula, the Vela Supernova Remnant, and prominent high-mass stars.…”

Section: Other Prominent Sources In the Fieldmentioning

confidence: 99%

A Low Frequency Pilot Survey of Southern HII Regions in the Vela Constellation

Tremblay,

Bourke,

Green

et al. 2021

Preprint

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Atomic ionised regions with strong continuum emission are often associated with regions of high-mass star formation and low-frequency (<2 GHz) observations of these regions are needed to help build star formation models. The region toward the Vela Supernova Remnant is particularly interesting as it is a complex structure of recent supernova explosions and molecular clouds containing a number of H regions that are not well characterised. We searched publicly available catalogues for H regions, both candidate and identified, which also have low-frequency emission. In the area of ∼400 square degrees toward the Vela Supernova remnant, we found 10 such H regions, some of which have multiple components in catalogues. In this work we use data from the Australian Square Kilometre Array Pathfinder and previously unpublished data from the Murchison Widefield Array and the Australian Telescope Compact Array to analyse these sources. The high-mass star forming region RCW 38, with observations specifically targeted on the source, is used as a pilot study to demonstrate how low-frequency, wide-field continuum observations can identify and study H regions in our Galaxy. For the 9 other H regions, we discuss their properties; including information about which clouds are interacting, their ages, whether they are dominated by infrared or optical H𝛼 lines, distances, ionising photon flux, and upper limits on the infrared luminosity. In future work, these 9 regions will be analysed in more detail, similar to the result for RCW 38 presented here.

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A Galactic Plane Defined by the Milky Way H ii Region Distribution

Cited by 32 publications

References 45 publications

Autonomous Gaussian decomposition of the Galactic Ring Survey

Autonomous Gaussian decomposition of the Galactic Ring Survey

Estimating Dust Attenuation From Galactic Spectra. II. Stellar and Gas Attenuation in Star-forming and Diffuse Ionized Gas Regions in MaNGA

A Low Frequency Pilot Survey of Southern HII Regions in the Vela Constellation

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